backside vs rump

backside

noun
  • A person's buttocks. 

  • Used other than figuratively or idiomatically: see back, side. 

  • The back side of an estate: the backyard and outbuildings behind a main house, especially (UK dialect, euphemistic) an outhouse. 

  • The reverse or opposite of anything. 

adj
  • Used other than figuratively or idiomatically: see back, side. 

  • Approaching an obstacle backward 

rump

noun
  • The buttocks. 

  • A cut of meat from the rump of an animal. 

  • The hindquarters of a four-legged mammal, not including its legs 

  • A remnant, as in Rump Parliament. 

verb
  • To turn one's back on, to show one's (clothed) backside to, as a sign of disrespect. 

  • To fuck. (Compare bum (verb).) 

  • To cheat. 

  • To ramble; to move (or talk) aimlessly. 

  • To move (someone or something) around. 

How often have the words backside and rump occurred in a corpus of books? (source: Google Ngram Viewer )